1. Field of the Invention
The present invention relates to an ion generating apparatus, and more particularly to anion generating apparatus which is capable of effectively generating ions.
2. Description of the Related Art
The ion generating apparatus is an apparatus for ionizing air particles by generating an electric field around an electrode needle to which an electric voltage has been applied. The generated ion is used for the elimination of electrical charges on an electrically charged object or in the atmosphere. In order to generate the electric field in cooperation with the electrode needle, the ion generating apparatus includes a grounded metal or another electrode applied with counter polarity as a counter electrode.
In order to obtain a sufficient amount of ions, it is necessary for the ion generating apparatus to generate a strong electric field. As a method for obtaining the strong electric field, the counter electrode may be arranged in proximity to the electrode needle. However, this has been a problem incases where a distance between the counter electrode and the electrode needle is too small, because the counter electrode may be short circuited, and thus a sufficient amount of ions cannot be obtained.
In view of the above, the distance between the electrode needle and the counter electrode must be maintained in such a condition that the above-described short circuit will not happen. However, in cases where the electrode needle is protruded from a body of the ion generating apparatus sufficiently to ensure the distance from the counter electrode, this will lead to upsizing of the ion generating apparatus.
In general, when the ion generating apparatus is used for elimination of electric charge on an electrically charged object, the ion generating apparatus is used together with a down flow apparatus. The down flow apparatus generates downward air streams so that the generated ions may rapidly reach the electrically charged object. However, there has been a problem in that the upsized ion generating apparatus may disturb the air streams flowing from the down flow apparatus and decrease the flow rate of the air streams.
There has been another problem in that the ion generating apparatus is, in many cases, exposed to dust contained in the air streams from the down flow apparatus and contaminants such as water due to humidity in a factory. In such cases, the dust and water may adhere to the electrode needle which projects from the body of the ion generating apparatus and the counter electrode. Therefore, short circuiting can easily occur between the electrode needle and the counter electrode for generating the electric field, and thus the electric field sufficient for generating ions cannot be obtained.
In view of the above, it is a first object of the invention to provide an ion generating apparatus in which an electric field sufficient for generation of ions can be obtained between the electrode needle and the counter electrode, and at the same time, a short circuit can be prevented.
It is a second object of the invention to provide an ion generating apparatus which is made compact.
The above-mentioned objects can be achieved by providing an ion generating apparatus for generating ions by ionizing gas particles, according to the invention, comprising:
an electrode needle supplied with electric voltage for generating ions;
an electrode holding part made of insulating material, for holding said electrode needle so that a distal end portion of said electrode needle is in an exposed state;
a body part made of an insulating material, for supporting said electrode holding part projecting from one side face of said body part, said body part including a voltage supply section for supplying the electric voltage to said electrode needle; and
a counter electrode disposed on the one side face of said body part where said electrode needle exists so that at least a portion of said counter electrode is in contact with said body part,
wherein at least one of said body part and said electrode holding part has a surface discharge restraining part in a convex or concave shape for restraining surface discharge along a surface discharge path created between said electrode needle and said counter electrode through said electrode holding part.
Here, the surface discharge, which is also called creepage discharge, means discharge (or current leakage) may occur along the surface of the electrode holding part made of insulating material or the body part made of the insulating material between the electrode needle and the counter electrode.
According to the invention, because the electrode holding part between the electrode needle and the counter electrode is provided with the surface discharge restraining part in a convex or concave shape for restraining the surface discharge, the surface discharge distance is substantially enlarged. Accordingly, the electric field sufficient for generation of ions can be obtained between the electrode needle and the counter electrode, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it will be possible to conduct effective generation of ions.
In the above-mentioned ion generating apparatus, it is preferable that the electrode holding part is in a substantially cylindrical shape extending along an axial direction of the electrode needle, and the surface discharge path includes a path from the distal end portion of the electrode needle to the counter electrode through a peripheral face of the cylindrical electrode holding part.
With such a structure, and because the electrode holding part may be in a substantially cylindrical shape, and the surface discharge path includes the path from the distal end portion of the electrode needle to the counter electrode through the peripheral face of the cylindrical electrode holding part, the electric field sufficient for generation of ion can be obtained between the electrode needle and the counter electrode, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it will be possible to conduct effective generation of ions.
Further, in the above-mentioned ion generating apparatus, it is preferable that the surface discharge restraining part is integrally provided on the peripheral face of the cylindrical electrode holding part, and has the convex or concave shape extending in a circumferential direction of the electrode holding part.
With this structure, and because the surface discharge between the electrode needle and the counter electrode will be effectively restrained, the electric field sufficient for the generation of ions can be obtained, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it will be possible to conduct effective generation of ion.
In the above-mentioned ion generating apparatus, it is also preferable that the counter electrode is attached to the body part at a position apart from a support position in the body part for supporting the electrode holding part while being disposed close to the electrode holding part keeping such a spatial distance between them that the counter electrode can generate an electric field for generating ions in cooperation with the electrode needle.
With this structure, and because the surface discharge between the electrode needle and the counter electrode and atmospheric discharge between the electrode needle and the electrode holding part can be restrained, the electric field sufficient for generation of ions can be obtained, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it is possible to conduct effective generation of ions.
Further, in the above-mentioned ion generating apparatus, it is preferable that the spatial distance is such a distance that atmospheric discharge is restrained between the surface discharge restraining part of the electrode holding part and the counter electrode.
With this structure, and because the atmospheric discharge is restrained between the surface discharge restraining part of the electrode holding part and the counter electrode, the electric field sufficient for the generation of ions can be obtained, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it will be possible to conduct effective generation of ion.
Further, in the ion generating apparatus, it is preferable that the body part is in a shape of an elongated bar, and provided with a plurality of the electrode holding parts spaced from each other in a longitudinal direction thereof.
In this structure, and because the plurality of electrode holding parts are spaced from each other so as to form a certain width, electrical charges on an electrically charged object having a considerable width can be effectively eliminated.
Further, in the above-mentioned ion generating apparatus, it is preferable that the counter electrode includes a plurality of openings through which the electrode holding parts can independently protrude, and the spatial distance is the shortest distance between circumferential edges of the openings and the electrode holding parts protruding from the openings.
With this structure, and because the counter electrode includes a plurality of openings, and the spatial distance is the shortest distance between the circumferential edges of the openings and the electrode holding parts protruding from the openings, the electric field sufficient for the generation of ions can be obtained, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it is possible to conduct the effective generation of ions.
In the above-mentioned ion generating apparatus, it is also preferable that the counter electrode consists of a metal plate having a substantially U-shape cross section and having substantially the same length as the body part in the elongated bar shape, and both sides of the metal plate in the U-shape are in contact with the body part.
With this structure, and because the counter electrode consists of a metal plate with a U-shape cross section, and an open edge of the U-shape is in contact with longitudinal edges of the body part, the electric field sufficient for the generation of ions can be obtained, and at the same time, a short circuit can be prevented. In addition, because the ion generating apparatus can be made compact, it is possible to conduct the effective generation of ions.
In short, as disturbance of the air streams for allowing the generated ions to reach the electrically charged object by means of a down flow apparatus can be restrained to a minimum extent and thus sufficient ions can reach the electrically charged object, effective elimination of electrical charges can be attained.